The present invention is directed to the delivery of energy to consumers, and more particularly to a system which integrates on-site energy generation capabilities with conventional centralized power distribution networks.
Conventionally, the delivery of various types of energy to consumers, such as industries, commercial entities, and residential customers, has been carried out by regulated agencies. For example, in the United States the distribution of electrical power has been serviced by a few thousand regulated monopoly franchises. In many cases, all of the energy customers within a given geographic area rely upon a single electrical power distribution company for their entire supply.
From the standpoint of the customer, certain inconveniences are associated with the concentration of power distribution in a single entity. Foremost among these is the reliability with which the power is delivered. The ability of a power company to deliver adequate amounts of energy to all of its customers is dependent upon a variety of factors. Among these factors, the one which has perhaps the most significant impact is the weather. Catastrophic weather conditions, such as hurricanes, tornadoes, ice storms, and the like, can severely disrupt the power distribution facilities, causing customers to lose access to power for hours, days or even weeks at a time. Increasingly volatile weather patterns have exacerbated this problem. Power reliability is also adversely impacted by construction and motor vehicle accidents that disrupt power lines.
Another factor, which is sometimes related to the weather, is usage. For instance, during hot summer months, the demands of air conditioning and refrigeration systems may surpass the capacity of the power distribution system during peak periods. As a result, the amount of power delivered to each customer is reduced, resulting in so-called xe2x80x9cbrown-outxe2x80x9d conditions. Under these conditions, certain types of equipment may not operate properly, or may fail to operate at all, due to voltage levels that are below minimum specifications, and/or fluctuations that are created by an electrical utility in balancing of loads. This problem becomes more acute with the increasing use of various types of low-power digital electronic equipment, such as computers, which are much more sensitive to variations in voltage levels. Frequent fluctuations in power quality such as dips, surges, sags and spikes are a significant source of annoyance and disruption to consumers. These and other power quality inconsistencies are driven mainly by the factors described above: weather, accidents and grid congestion.
Another source of inconvenience associated with centralized power distribution is the unpredictability of costs. The cost to traditional utilities of providing power to consumers changes with the season and time of day, in large part due to scarcity of distribution capacity. In an effort to persuade consumers to reduce their usage during peak periods, energy companies may impose higher rates on power consumption based on time of day or power grid usage levels. As a result, consumer""s bills are significantly increased if they must use power during these times, making it more difficult to predict monthly or yearly energy costs.
Finally, centralized power generation has deleterious environmental impacts. Key environmental concerns associated with power plants are air emissions, water use and aesthetic objections. The distribution and transmission grid also poses both aesthetic and potential environmental hazards. Government regulations to make power generation more environmentally friendly, as well as on plant and grid construction, have imposed new cost pressures on power plants, thereby increasing the price of the energy to the consumer.
In an effort to alleviate some of these inconveniences, particularly those associated with the unreliability of power delivery, consumers may install a local back-up system. Typically, this type of system may comprise one or more electric power generators that operate on fuels such as natural or liquid gas. These generators are designed to replace, or supplement, the power delivered via a centralized electric power grid during those times when the centralized power is not available, or is insufficient to meet the consumer""s needs.
While the use of local generators provides some relief when centralized power is not available, they do not offer a totally satisfactory solution. For instance, the purchase of the generators, and all related equipment, can represent a significant up-front investment for the consumer, which may take years to pay for itself. Furthermore, the consumer is required to perform regular maintenance on the generation equipment, even though it may not be used for a considerable period of time. In addition, the quality of the power delivered by local generators may be insufficient to meet the consumer""s needs, and are therefore limited to use in emergency conditions.
It is an objective of the present invention, therefore, to provide on-site power generation capabilities to consumers that can be integrated with the power delivered via a computer-driven centralized network, to thereby ensure the reliable availability of power at a predictable rate, while avoiding the inconveniences typically associated with consumer-owned generation equipment.
Pursuant to the foregoing objectives, the present invention comprises a method and system in which one or more electric power generators are located at or near a consumer""s premises, to provide power which is dedicated to the needs of that consumer. In one embodiment of the invention, the power provided by the on-site generators complements that which is delivered via a centralized power grid network. For example, the on-site generators can be normally configured to provide power to critical components of the consumer, such as refrigeration equipment, and the power requirements of other equipment can be supplied by the power grid. In the event that the power grid is disabled, or is otherwise unable to provide adequate power to the consumer, the on-site generators can be switched to provide power to the other equipment in lieu of, or in addition to, the principally supported components. If necessary, the power that is supplied to the critical equipment, such as refrigeration, can be cycled on and off, to balance the load on the generators.
In a further embodiment of the invention, a central control facility selectively actuates the on-site generator(s) to intelligently arbitrage between the locally generated power and that which is provided via the grid network, based on a variety of factors. For example, the instantaneous cost of power supplied via the grid network is provided to a processor in the control facility, where it is compared against stored costs of operating the on-site generators. These costs might include the price of fuel required to run the generators, maintenance expenses, other types of service and installation expenses, and finance charges, if applicable. When all of these costs are less than that power company""s charges for the power provided by the grid network, the central control system can selectively actuate the on-site generators, to partially or totally replace power delivered via the grid. Since the costs for operating the generators are known in advance, to a large degree, it becomes possible to guarantee the consumer a maximum price for its power needs.
In addition to price-based considerations, other factors can also be employed in the decision whether to activate the on-site generators. For example, data relating to weather conditions and peak usage periods can be employed to actuate the generators at times when the delivery of power via the grid is likely to be interrupted or unreliable. In some cases, the utility may be willing to buy back some of the power which it would otherwise provide to the consumer during peak usage periods, which can influence the decision to employ on-site generation.
As another factor, historical data regarding the consumer""s power usage can be employed to predict times when the usage requirements are likely to be high, and thereby actuate the generators to supplement or replace the power provided from the grid.